JP2006171214A - Method for manufacturing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing toner by which fixing property can be improved without degrading charging property on manufacturing the toner by using a crystalline polyester together with an amorphous resin, and excellent images can be continuously obtained without inducing deterioration in the picture quality even when continuous printing is performed in a high-speed machine. <P>SOLUTION: A melting and kneading step is carried out using a kneading machine having as structural members, at least a plurality of barrels connected to one another and individually temperature controllable, and a screw having one or more kneading portions and two or more conveying portions, inserted into the connected plurality of barrels. The screw has at least one kneading portion in a part from the source supply side to 0.5Lt (Lt represents the whole length of the kneading machine). A set temperature T<SB>1</SB>in a barrel (X) including a kneading portion positioned nearest to the source supply port, a set temperature T<SB>2</SB>in a barrel adjacent in the source supply port side to the barrel (X) including the kneading portion, and the melting point Tc of the crystalline polyester satisfy inequalities (a): 0°C≤T<SB>1</SB>-T<SB>2</SB>≤50°C and (b): 5°C≤Tc-T<SB>1</SB>≤35°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like.

  In recent years, the demand for on-demand printing has increased, and there has been a demand for toner that can cope with high image quality and high speed.

  From the viewpoint of improving the fixing property, a toner containing a crystalline polyester as a binder resin has been studied particularly for the purpose of improving low-temperature fixing (see Patent Document 1 and Patent Document 2). There are many points to improve. This is presumably because when crystalline polyester is used in combination with an amorphous resin, the difference in viscosity between the two is large, and a sea-island structure is likely to occur, resulting in poor dispersion of internal additives such as charge control agents.

  Therefore, a technique for improving the dispersibility of the internal additive has been proposed from the toner production method. For example, a method for producing the kneading machine under the condition that the temperature is lowered from the raw material inlet (see Patent Document 3), the kneading machine temperature setting zone is divided, and the setting temperature and the discharge temperature of the kneaded material are combined. There has been reported a production method that defines the relationship between the thermal characteristics of the adhesive resin (see Patent Document 4).

However, in a toner using crystalline polyester, it is not sufficient to use these techniques because of the special properties of the resin properties.
JP 2001-222138 A (Claim 1) JP 2004-61875 A (Claim 1) JP 2002-229262 A (Claim 1) JP-A-9-146301 (Claim 1)

  An object of the present invention is to improve the fixability without impairing the chargeability in the case of producing a toner using a combination of a crystalline polyester and an amorphous resin as a binder resin, and continuously printing on a high-speed machine. In particular, it is an object of the present invention to provide a method capable of producing a toner capable of continuously obtaining excellent images without causing image quality deterioration.

The present invention is a method for producing a toner having a melt kneading step, a cooling step, a pulverizing step, a classification step, and a surface treatment step of a raw material containing a binder resin and a colorant,
The binder resin contains 1 to 40% by weight of crystalline polyester and an amorphous resin,
The melt-kneading step has at least a plurality of coupled barrels capable of individually setting the temperature, and one or more kneading units and two or more conveying units inserted into the coupled plurality of barrels. Using a screw as a constituent member, using an extrusion kneader having a raw material supply port at one end of the connected barrel and a kneaded product discharge port at the other end,
The screw has at least one kneading section between the raw material supply side and 0.5 Lt (Lt indicates the total length of the kneader), and includes a barrel (X ) T ₁ the set temperature in, when kneading unit barrel including (X) and a raw material supply port of the adjacent barrel side set temperature T _2, and the melting point of the crystalline polyester and Tc, expression ( a) and (b):
0 ℃ ≦ T ₁ −T ₂ ≦ 50 ℃ (a)
_{5 ℃ ≦ Tc-T 1 ≦} 35 ℃ (b)
The present invention relates to a toner production method that satisfies

  According to the present invention, even when a crystalline polyester and an amorphous resin are used in combination as a binder resin, the fixability can be improved without impairing the chargeability, and the image quality is deteriorated even when continuously printing on a high-speed machine. A toner capable of continuously obtaining excellent images without being produced can be produced.

  When crystalline polyester and an amorphous resin are used as a binder resin, the fixability is improved, but it may cause a decrease in chargeability due to a decrease in dispersibility of the internal additive. Therefore, the present inventors have studied a method that can uniformly disperse the internal additive even when the crystalline polyester and the amorphous resin are used in combination.

  For example, as a means for mixing the raw materials more uniformly, for example, there is a method of using a dispersant. However, there is a concern that the use of the dispersant may have an adverse effect on chargeability or an influence from environmental changes.

  In addition, as a means for melt-kneading the raw material more uniformly, for example, there is a method of performing melt-kneading twice, but performance degradation and productivity due to thermal decomposition of the raw material due to excessive heat application and resin chain breakage There is concern about the decline.

  Therefore, as a result of investigation by the present inventors, by adjusting the heating temperature at the time of melt-kneading, even if a crystalline polyester and an amorphous resin are used as the binder resin, an internal additive such as a charge control agent is used. It was found that the toner can be uniformly dispersed in the binder resin, and a toner excellent in fixing property and charging property can be obtained.

  Hereinafter, each step in the toner production method of the present invention will be described.

  In the present invention, at least a binder resin containing a crystalline polyester and a colorant are used as raw materials to be subjected to melt kneading.

  In the present invention, the “crystalline” resin means that the ratio of the softening point to the maximum peak temperature of the heat of fusion (softening point / peak temperature) is 0.6 to 1.3, preferably 0.9 to 1.2, more preferably greater than 1.0 and 1.2 or less. The term “amorphous” resin refers to a resin having a ratio of the softening point to the maximum peak temperature of heat of fusion (softening point / peak temperature) of greater than 1.3 and less than or equal to 4.0, preferably 1.5 to 3.0. .

  In the present invention, the maximum peak temperature of the heat of fusion of the crystalline polyester is preferably 60 to 150 ° C, more preferably 80 to 140 ° C, and further preferably 100 to 130 ° C, from the viewpoints of fixability, storage stability and durability.

  The crystalline polyester in the present invention is an alcohol component containing 60 mol% or more of an aliphatic diol having 2 to 6, preferably 4 to 6 carbon atoms, and 2 to 8, preferably 4 to 6, more preferably carbon atoms. Is preferably a resin obtained by polycondensation of a carboxylic acid component containing 60 mol% or more of the aliphatic dicarboxylic acid compound 4.

  Examples of the aliphatic diol having 2 to 6 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Neopentyl glycol, 1,4-butenediol and the like are mentioned, and α, ω-linear alkanediol is particularly preferable.

  The aliphatic diol having 2 to 6 carbon atoms is preferably contained in the alcohol component in an amount of 60 mol% or more, more preferably 80 to 100 mol%, still more preferably 90 to 100 mol%. In particular, it is desirable that one aliphatic diol in them accounts for 70 mol% or more, preferably 80 to 95 mol% in the alcohol component. Among these, 1,4-butanediol is preferably contained in the alcohol component in an amount of preferably 60 mol% or more, more preferably 70 to 100 mol%, and still more preferably 80 to 100 mol%.

  The alcohol component may contain a polyhydric alcohol component other than the aliphatic diol having 2 to 6 carbon atoms. As the polyhydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4 -Hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane and other bisphenol A alkylene (2 to 3 carbon) oxide (average added mole number 1 to 10) adduct And trivalent or higher alcohols such as glycerin, pentaerythritol, and trimethylolpropane.

  Examples of the aliphatic dicarboxylic acid compound having 2 to 8 carbon atoms include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, and anhydrides of these acids, alkyl (C1-C3) ester etc. are mentioned, In these, fumaric acid and adipic acid are preferable and fumaric acid is more preferable. As described above, the aliphatic dicarboxylic compound refers to an aliphatic dicarboxylic acid, its anhydride, and its alkyl (C1-3) ester. Among these, an aliphatic dicarboxylic acid is preferable.

  The aliphatic dicarboxylic acid compound having 2 to 8 carbon atoms is preferably contained in the carboxylic acid component in an amount of 60 mol% or more, more preferably 80 to 100 mol%, still more preferably 90 to 100 mol%. . In particular, one aliphatic dicarboxylic acid compound in them preferably accounts for 60 mol% or more, more preferably 70 to 100 mol%, and still more preferably 80 to 100 mol% in the carboxylic acid component. desirable. Among them, it is desirable that fumaric acid is contained in the carboxylic acid component in an amount of preferably 60 mol% or more, more preferably 70 to 100 mol%, and still more preferably 80 to 100 mol%.

  The carboxylic acid component may contain a polyvalent carboxylic acid component other than the aliphatic dicarboxylic acid compound having 2 to 8 carbon atoms. Examples of the polyvalent carboxylic acid component include phthalic acid, isophthalic acid, terephthalic acid and the like. Aromatic dicarboxylic acids; sebacic acid, azelaic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid aliphatic dicarboxylic acid; cyclohexane dicarboxylic acid and other alicyclic dicarboxylic acids; trimellitic acid, pyromellitic acid and other trivalents And polyhydric carboxylic acids as described above; and anhydrides and alkyl (C1-3) esters of these acids.

  The molar ratio of the carboxylic acid component to the alcohol component in the crystalline polyester (carboxylic acid component / alcohol component) is determined from the viewpoint of production stability, and when the alcohol component is larger, the molecular weight of the resin is reduced by evaporation during vacuum reaction. From the viewpoint of easy adjustment, 0.9 or more and less than 1.0 are preferable, and 0.95 or more and less than 1.0 are more preferable.

  In the production of crystalline polyester, polycondensation of an alcohol component and a carboxylic acid component is performed by, for example, combining an alcohol component and a carboxylic acid component in an inert gas atmosphere, if necessary, an esterification catalyst, a polymerization inhibitor, And can be carried out by reacting at a temperature of 120 to 230 ° C. Specifically, all monomers are charged at once to increase the strength of the resin, or divalent monomers are first reacted to reduce low molecular weight components, and then trivalent or higher monomers. A method of adding and reacting may be used. Further, the reaction may be accelerated by reducing the pressure of the reaction system in the latter half of the polymerization.

  In addition, it is preferable to make high molecular weight the crystalline polyester in this invention, and it is preferable to make it react until the reaction liquid viscosity becomes high. In order to obtain a high molecular weight crystalline polyester, as described above, the molar ratio of the carboxylic acid component and the alcohol component is adjusted, the reaction temperature is increased, the amount of catalyst is increased, and the dehydration reaction is performed for a long time under reduced pressure. The reaction conditions such as these may be selected. A high-power motor can be used to produce a high molecular weight crystalline polyester. However, when producing without particularly selecting production equipment, the raw material monomer is used as a non-reactive low-viscosity resin or solvent. The method of reacting together is also an effective means.

  Furthermore, the crystalline polyester in the present invention is obtained by, for example, adding a wax to the reaction system of the raw material monomer of the crystalline polyester and subjecting the alcohol component and the carboxylic acid component, which are the raw material monomers, to condensation polymerization in the presence of the wax. It is preferable to be obtained. It has been found that the use of wax as the raw material for the crystalline polyester increases the dispersibility of the raw materials used in the toner, although the detailed reason is unknown. This is probably because the sea-island structure due to the difference in viscosity between the crystalline polyester and the amorphous resin is suppressed by the presence of the wax.

  The wax may be added to the raw material monomer at the beginning of the polymerization reaction, during the reaction after the start of the polymerization reaction, or continuously or intermittently from the beginning of the polymerization reaction to the end thereof.

The wax may be any of hydrocarbon wax, ester wax, amide wax, etc., but hydrocarbon wax is preferred from the viewpoint of compatibility with the crystalline resin and releasability. The hydrocarbon wax generally has a main skeleton represented by — (CH ₂ —CH (R)) _n — (wherein R represents a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms), Specific examples include polyethylene waxes such as Fischer-Tropsch wax, polypropylene wax, polyethylene-polypropylene wax, microcrystalline wax, and paraffin wax. Among these, from the viewpoint of improving the grindability of the crystalline resin, polyethylene wax and Polypropylene wax is preferred, and polypropylene wax is more preferred.

  The melt viscosity at 180 ° C. of the wax is preferably 0.03 Pa · s or more from the viewpoint of compatibility with the crystalline polyester, and preferably 0.2 Pa · s or less from the viewpoint of fixability. From these viewpoints, the viscosity of the wax is preferably 0.03 to 0.2 Pa · s, more preferably 0.04 to 0.19 Pa · s, and further preferably 0.05 to 0.18 Pa · s.

  The blending amount of the wax is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight, and further preferably 1 to 10 parts by weight with respect to 100 parts by weight of the obtained crystalline polyester.

  The dispersion diameter of the wax in the crystalline polyester is preferably 5 μm or more from the viewpoint of grindability, and is preferably 200 μm or less from the viewpoint of preventing exposure to the toner surface. From these viewpoints, the dispersion diameter of the wax is preferably 5 to 200 μm, more preferably 10 to 100 μm. The dispersion diameter of the wax can be adjusted by the raw material monomer, the type of wax, the stirring strength when polymerizing the raw material monomer, the cooling rate after polymerization, and the like.

  The number average molecular weight of the crystalline polyester is preferably from 3,000 to 10,000, more preferably from 5,000 to 9,000, and even more preferably from 6,000 to 8,000, from the viewpoints of storage stability and productivity.

  Further, from the viewpoint of durability, it is preferable that the crystalline polyester contains a high molecular weight component to some extent. Therefore, the weight average molecular weight of the crystalline polyester is preferably 150,000 to 8,000,000, more preferably 200,000 to 3,000,000, More preferably, 300,000 to 1,000,000.

  The content of the crystalline polyester is 1 to 40% by weight in the binder resin, preferably 3 to 35% by weight, and more preferably 5 to 30% by weight.

  In the present invention, the binder resin preferably further contains an amorphous resin in addition to the crystalline polyester.

  Examples of amorphous resins include amorphous resins, amorphous polyester polyamides, vinyl resins such as amorphous styrene-acrylic resins, hybrid resins having two or more resin components, and mixtures thereof. Among these, amorphous polyester, amorphous polyester polyamide, and hybrid resin in which an amorphous polyester component and a vinyl resin component are partially chemically bonded from the viewpoint of fixing property and compatibility with crystalline polyester. Is preferred, and amorphous polyester is more preferred.

Amorphous polyester can also be produced in the same manner as crystalline polyester. However, in order to make amorphous polyester,
(1) In the case of using a monomer that promotes crystallization of a resin such as an aliphatic diol having 2 to 6 carbon atoms or an aliphatic carboxylic acid compound having 2 to 8 carbon atoms, two or more of these monomers are used in combination. In any of the alcohol component and the carboxylic acid component, one of these monomers accounts for 10 to 70 mol%, preferably 20 to 60 mol% of each component, and two of these monomers Or more, preferably 2 to 4 types are used, or
(2) A monomer that promotes non-crystallization of the resin, preferably an alkylene oxide adduct of bisphenol A in the alcohol component, or succinic acid substituted with an alkyl group or alkenyl group in the carboxylic acid component In the acid component, it is preferable that 30 to 100 mol%, preferably 50 to 100 mol% is used in each of the two components.

  In addition to the polyhydric alcohol component and polyvalent carboxylic acid component, the amorphous polyester polyamide further comprises ethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, iminobispropylamine to form an amide component. Polyamines such as phenylenediamine, xylylenediamine and triethylenetetramine, aminocarboxylic acids such as 6-aminocaproic acid and ε-caprolactam, and aminoalcohols such as propanolamine are used as raw material monomers. Among these, hexamethylenediamine is used. And ε-caprolactam are preferred.

  Amorphous polyester polyamide can also be produced in the same manner as amorphous polyester.

  In the present invention, the hybrid resin may be obtained by using two or more kinds of resins as raw materials, or may be obtained from raw material monomers of one kind of resin and another kind of resin, and two more kinds. Although it may be obtained from a mixture of raw material monomers of the above resins, in order to obtain a hybrid resin efficiently, those obtained from a mixture of raw material monomers of two or more resins are preferred.

  Therefore, as a hybrid resin, raw material monomers of two polymerization resins each having an independent reaction path, preferably, a raw material monomer of a condensation polymerization resin and a raw material monomer of an addition polymerization resin are mixed, and the two polymerization reactions are performed. A resin obtained by carrying out the treatment is preferred, and specifically, a hybrid resin described in JP-A-10-087839 is preferred.

  Typical examples of the condensation polymerization resins include polyesters, polyester polyamides, polyamides, etc. Among them, polyesters are preferable, and typical examples of the addition polymerization resins include vinyl resins obtained by radical polymerization reaction, etc. Is mentioned.

  The softening point of the amorphous resin is preferably 70 to 180 ° C, more preferably 100 to 160 ° C, and the glass transition point is preferably 45 to 80 ° C, more preferably 55 to 75 ° C. The glass transition point is a physical property peculiar to an amorphous resin, and is distinguished from the maximum peak temperature of heat of fusion.

  In the present invention, as an amorphous resin, a low softening point resin having a softening point of 70 ° C. or higher and lower than 120 ° C. and a high softening point of 120 ° C. or higher and 160 ° C. or lower from the viewpoint of low temperature fixability and high temperature offset resistance. The softening point resin is preferably used in combination at a weight ratio of 20/80 to 80/20 (low softening point resin / high softening point resin).

  The weight ratio of the crystalline polyester to the amorphous resin (crystalline polyester / amorphous resin) is preferably 1/99 to 40/60 from the viewpoint of chargeability, storage stability, low-temperature fixability, and durability. / 97 to 35/65 is more preferred, and 5/95 to 30/70 is even more preferred.

  As the colorant used in the present invention, all of dyes and pigments used as toner colorants can be used. Carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, Rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, disazo yellow and the like can be used, and these can be used alone or in admixture of two or more. , Black toner, color toner, and full color toner. The content of the colorant is preferably 1 to 40 parts by weight and more preferably 3 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner material of the present invention includes a charge control agent, a release agent, a conductivity adjusting agent, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, a fluidity improver, and an improved cleaning property. An additive such as an agent may be appropriately contained.

  Charge control agents include nigrosine dyes, triphenylmethane dyes containing tertiary amines as side chains, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives and other positively chargeable charge control agents and metal-containing azo dyes, copper Examples include negatively chargeable charge control agents such as phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, and boron complexes of benzylic acid. The content of the charge control agent is preferably 0.1 to 8 parts by weight and more preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the binder resin.

  The toner obtained by the present invention can be used for both positively and negatively chargeable toners, but has excellent low-temperature fixability and can stably supply excellent image quality. It can be suitably used for a high-speed machine having a selenium photoreceptor, and is preferably used as a positively chargeable toner.

  When the toner obtained according to the present invention is used as a positively chargeable toner, it is preferable to use a nigrosine dye or / and a quaternary ammonium salt compound as a positively chargeable charge control agent from the viewpoint of charge level.

  Nigrosine dye is a black mixture consisting of a large number of components generally obtained by condensation polymerization of nitrobenzene and aniline in the presence of a metal catalyst, and its structure has not been fully clarified, but it is a modified product by resin acid, etc. , Including Nigrosine Base EX, Oil Black BS, Oil Black SO, Bontron N-01, Bontron N-04, Bontron N-07, “Bontron N-09”, “Bontron N-11”, “Bontron N-21” (manufactured by Orient Chemical Industries), “Nigrosin” (manufactured by Ikeda Chemical), “Spirit Black No.850”, “Spirit Black No. 900 ”(manufactured by Sumitomo Chemical Co., Ltd.).

  The content of the nigrosine dye is preferably 0.2 to 5 parts by weight and more preferably 0.5 to 4 parts by weight with respect to 100 parts by weight of the binder resin.

  As a quaternary ammonium salt compound, the formula (I):

(In the formula, R ^{1 to} R ⁴ may be the same or different, and may be substituted with a halogen atom, a lower alkyl group having 1 to 8 carbon atoms, an alkyl group or alkenyl group having 8 to 22 carbon atoms, or A compound represented by an aryl group or aralkyl group having 6 to 20 carbon atoms, and X ⁻ represents an anion) is preferable.

In the present invention, R ^{1 to} R ⁴ are each a lower alkyl group having 1 to 4 carbon atoms which may be substituted with a halogen atom, or a carbon number, since the charging characteristics are more stable and the fixability can be improved. 12-18 alkyl groups, phenyl groups or benzyl groups are preferred, and X ⁻ is an aromatic sulfonate ion such as toluenesulfonate ion or hydroxynaphthalenesulfonate ion, aromatic carboxylate ion, molybdate ion, tungstic acid Ions, halogen ions or hydroxy ions are preferred, and aromatic sulfonate ions, aromatic carboxylate ions and molybdate ions are more preferred.

  In the present invention, in particular, the formula (Ia):

A compound represented by formula (Ib):

And a compound represented by formula (Ic):

At least one selected from the group consisting of compounds represented by formula (Ib) is preferred, and a compound represented by formula (Ib) is more preferred.

  “TP-415” (made by Hodogaya Chemical Co., Ltd.) is a commercially available product containing the compound represented by the formula (Ia), and “COPY” is a commercially available product containing the compound represented by the formula (Ib). Examples of commercially available products containing the compound represented by the formula (Ic) such as “CHARGE PSY” (manufactured by Clariant Japan) include “Bontron P-51” (manufactured by Orient Chemical Industries).

  The content of the quaternary ammonium salt compound is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and still more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the binder resin.

  Further, from the viewpoint of charging stability and rising, it is preferable to use a nigrosine dye and a quaternary ammonium salt compound in combination, and the quaternary ammonium salt compound / nigrosine dye (weight ratio) is preferably 1/100 to 100/100, More preferred is 10/100 to 70/100.

  Examples of the release agent include ester waxes such as carnauba wax and rice wax, synthetic waxes such as polypropylene wax, polyethylene wax, and Fischer Tropu, coal waxes such as montan wax, and waxes such as alcohol waxes. May be contained alone or in admixture of two or more. Among these, from the viewpoint of low-temperature fixability, ester wax having a melting point of 60 to 90 ° C. is preferable, and carnauba wax is more preferable. The content of the wax is preferably 0.1 to 10 parts by weight and more preferably 0.2 to 9 parts by weight with respect to 100 parts by weight of the binder resin.

  In the present invention, raw materials containing a binder resin, a colorant and the like are Nauter mixer (manufactured by Hosokawa Micron Co.), Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), super mixer (manufactured by Kawata Co., Ltd.), high speed mixer (Fukae Kogyo Co., Ltd.) Manufactured) and a Ladige mixer (manufactured by Matsubo Co., Ltd.) and the like, and after mixing the materials uniformly, it is preferably subjected to a melt-kneading step.

  In the raw material melt-kneading step, at least a plurality of coupled barrels that can be individually set in temperature, one or more kneading units and two or more conveying units inserted into the coupled plurality of barrels. An extrusion kneader is used which has a screw as a constituent member, a raw material supply port at one end of a connected barrel, and a kneaded product discharge port at the other end.

  In the present invention, for example, a single screw extruder into which one screw is inserted or a twin screw extruder into which two screws are inserted can be used as the extrusion kneader, but the discharge is stable. A twin screw extruder is preferred from the standpoints that there is little stagnation and that melt kneading can be performed in a short time and that the resin temperature can be accurately controlled.

  Commercially available extrusion kneaders used in the present invention include KTK type twin screw extruder (manufactured by Kobe Steel), TEM type twin screw extruder (manufactured by Toshiba Machine Co., Ltd.) and PCM type twin screw extruder (Ikegai Iron Works). Among them, a PCM type twin screw extruder (manufactured by Ikekai Tekko Co., Ltd.) is preferable.

  A screw may be equipped with a plurality of parts having different shapes according to the purpose for one shaft, and the plurality of parts are connected to form a single screw. It may be a thing.

  The screw has, depending on the shape of the part, a kneading part mainly having the main function of melting and kneading the raw material and a conveying part mainly having the main function of conveying the raw material or the melt-kneaded product (for example, “Development of toner / Practical application general technical data collection "(September 30, 1985, published by Japan Science Information Co., Ltd., publishing department, page 242), Japanese Patent Laid-Open No. 10-133413 (Figs. 1-10) etc.). The screw of the extrusion kneader used in the present invention has at least one kneading section between the raw material supply side and 0.5 Lt (Lt indicates the total length of the kneading machine). It is preferable to have 2 or more, and it is preferable to have at least one kneading part between 0.5 Lt from the raw material supply side and 0.5 Lt from the kneaded product discharge port.

  In the present invention, the kneading part at least a part of which is on the position of 0.5 Lt is also included in the kneading part located between the raw material supply side and 0.5 Lt.

  The screw is rotatable, and the number of rotations can be adjusted as appropriate, but is preferably 60 to 300 r / min, more preferably 70 to 250 r / min.

  The length of each kneading part is preferably 0.02 Lt to 0.125 Lt, and more preferably 0.04 Lt to 0.125 Lt.

  The number of barrels to be coupled is not particularly limited, but is preferably coupled at least for each kneading unit and conveyance unit.

In this invention, when using the extrusion kneader which has the said structure where the barrel which can set temperature individually was connected, it has a big characteristic in the temperature setting in a barrel. That is, in the present invention, the set temperature in the barrel (X) including the kneading part located closest to the raw material supply port side is T ₁ , and the barrel (X) including the kneading part is adjacent to the raw material supply port side. Where T _{2 is} the set temperature and Tc is the melting point of the crystalline polyester, the formulas (a) and (b):
0 ℃ ≦ T ₁ −T ₂ ≦ 50 ℃ (a)
_{5 ℃ ≦ Tc-T 1 ≦} 35 ℃ (b)
Satisfied. Here, Tc refers to the maximum peak temperature of heat of fusion of crystalline polyester.

  In the present invention, by adjusting the set temperature in the barrel according to the formulas (a) and (b), the crystalline polyester can be uniformly dispersed with an appropriate dispersion diameter, whereby internal additives such as a colorant can be added. A toner in which the agent is uniformly dispersed can be obtained. It is presumed that the formula (a) mainly contributes to the control of the uniform dispersion of the crystalline polyester, and the formula (b) contributes to the control of the dispersion diameter of the crystalline polyester.

Expression (a) means that the set temperature of the barrel is increased from the raw material supply port toward the kneading section. That is, by providing such a temperature gradient, the kneading share can be effectively increased when the raw material is conveyed to the kneading section, and therefore it is estimated that the dispersibility is improved. In the formula (a), 5 ° C. ≦ T ₁ −T ₂ ≦ 45 ° C. is preferable, and 10 ° C. ≦ T ₁ −T ₂ ≦ 40 ° C. is more preferable.

Formula (b) means melt-kneading the set temperature of the barrel immediately before the kneading part at a temperature lower than the melting point of the crystalline polyester used in the present invention. In melt-kneading, the softening point of the amorphous resin and the melting point of the crystalline polyester have a complex effect on the kneading state, but the detailed reason is unknown by setting such a temperature, but the crystalline polyester Can be dispersed without destroying its crystallinity. In the formula (b), 7 ° C. ≦ Tc−T ₁ ≦ 30 ° C. is preferable, and 10 ° C. ≦ Tc−T ₁ ≦ 25 ° C. is more preferable.

The set temperatures of the barrels on the kneaded product discharge port side from the barrel (X) including the kneading part located closest to the raw material supply port side are preferably all within the range of T ₁ ± 5 ° C., and all the barrels (X) more preferably the set temperature and the same temperature, that is, T _1.

  Next, the obtained melt-kneaded product is subjected to a cooling step of cooling until reaching a grindable hardness. Examples of the cooling means include an air cooling method, a water cooling method, a steel cooling belt method, and the like. Among these, a water cooling method is preferable from the viewpoint of cooling efficiency. In order to increase the cooling efficiency, it is preferable to cool the melt-kneaded product after rolling it with a rolling roll or a rolling drum.

  In the subsequent pulverization step, the melt-kneaded product is pulverized until a desired toner particle size is reached. Such pulverization may be performed at one time, but from the viewpoint of pulverization efficiency and the like, it is preferable to pulverize to a desired toner particle size after coarse pulverization in advance.

  The pulverizer used in the present invention is not particularly limited, but as a pulverizer suitable for coarse pulverization, a cutter mill, a rotoplex, an atomizer, etc., as a pulverizer suitable for fine pulverization, a jet mill, a collision plate mill, Examples thereof include a rotary machine mill.

The volume median particle size (D ₅₀ ) of the coarsely pulverized product is preferably 1 to 3 mm, more preferably 1.2 to 2.8 mm, and more preferably 1.4 to 2.6 mm from the viewpoint of enhancing the heat dissipation effect and preventing the wax from being detached. Is more preferable. In the present specification, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  Examples of the classifier used in the classification process for classifying the pulverized product include an air classifier, an inertia classifier, and a sieve classifier. In the classification step, the pulverized product that has been removed due to insufficient pulverization may be subjected to the pulverization step again.

The volume median particle size (D ₅₀ ) of the toner obtained by the classification step is preferably 4 to 16 μm, more preferably 5 to 14 μm.

  The surface treatment step is a step of adding an external additive to the toner surface. Examples of the external additive include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide. Among these, silica is preferable from the viewpoint of fluidity and durability.

Silica is preferably hydrophobic silica that has been hydrophobized from the viewpoint of chargeability. The hydrophobizing method is not particularly limited, and examples of the hydrophobizing agent include hexamethyldisilazane, dimethyldichlorosilane, silicone oil, methyltriethoxysilane, and the like. From the viewpoint, silicone oil is preferable. The treatment amount of the hydrophobizing agent is preferably 1 to 7 mg / m ² per surface area of silica.

  The blending amount of the external additive is preferably 0.01 to 10 parts by weight, and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner to be processed, from the viewpoints of chargeability and fluidity.

  The toner to be processed and the external additive can be mixed using various mixers such as a Henschel mixer and a super mixer. In addition, after mixing, it is desirable to perform a sieving step using a gyro shifter, an ultrasonic sieve, etc., preferably an ultrasonic sieve, to remove foreign substances.

  When the toner obtained by the present invention contains magnetic fine powder, it is used alone as a developer, and when it does not contain magnetic fine powder, it is used as a non-magnetic one-component developer or mixed with a carrier for two-component development. Although it can be used as an agent, in the present invention, it is preferably used as a two-component developer from the viewpoint of excellent durability.

  The toner obtained by the present invention can maintain good durability even when used in a high-speed printing machine having a linear speed of 370 mm / sec or more, preferably 500 mm / sec or more, more preferably 1000 mm / sec or more. . Here, the linear speed refers to the process speed of the printing press and is determined by the paper feed speed of the fixing unit.

[Softening point]
Using a Koka-type flow tester (CFT-500D, manufactured by Shimadzu Corporation), a 1 g sample was dried under reduced pressure for 4 hours, and then heated at a heating rate of 6 ° C / min. A nozzle with a diameter of 1 mm and a length of 1 mm is pushed out, and this draws a plunger drop amount (flow value) -temperature curve of the flow tester, h / 2 when the height of the S-curve is h The temperature corresponding to (the temperature at which half of the resin flows out) is defined as the softening point.

[Maximum peak temperature of melting heat and glass transition point]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210), the sample was heated to 200 ° C and then cooled to 0 ° C at a temperature decrease rate of 10 ° C / min. Determine the maximum peak temperature of heat of fusion. The glass transition point is defined as the temperature at the intersection of the base line extension below the maximum peak temperature in the measurement and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

[Acid value]
Measured by the method of JIS K0070.

[Number average molecular weight and weight average molecular weight]
The number average molecular weight and the weight average molecular weight are determined from a chart showing the molecular weight distribution by gel permeation chromatography obtained by the following method.
(1) Preparation of sample solution Dissolve the resin in chloroform to a concentration of 0.5g / 100ml. Next, this solution is filtered using a fluororesin filter having a pore size of 2 μm (FP-200, manufactured by Sumitomo Electric Industries, Ltd.) to remove insoluble components, thereby obtaining a sample solution.
(2) Molecular weight distribution measurement Flow chloroform at a flow rate of 1 ml per minute as a lysis solution, and stabilize the column in a constant temperature bath at 40 ° C. Measurement is performed by injecting 100 μl of the sample solution. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. For the calibration curve at this time, a sample prepared using several types of monodisperse polystyrene as a standard sample is used.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analytical column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Melt viscosity]
A viscoelasticity measuring device “RDA II” (manufactured by Rheometrics) is used for measurement under the following measurement conditions.
(Measurement condition)
Measurement jig: Curette is used. Upper tube (radius: 15 mm, length: 32 mm), lower vessel (radius: 25 mm), distance between the upper tube and the bottom of the vessel at the time of measurement 0.5 mm
Measurement sample: 8g
Measurement frequency: 2rad / sec
Measurement temperature: 180 ℃
Measurement distortion: Measure 20 points in 0.5% increments from 0.5% to 10% in automatic measurement mode.
Measured value: The average value of 18 points excluding the maximum and minimum values from the 20 measured values.

Production Example 1 of Crystalline Polyester
The raw materials shown in Table 1 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and maintained at 140 ° C. for 4 hours. The temperature was raised from 140 ° C. to 160 ° C. at a rate of 10 ° C./hour and from 160 ° C. to 200 ° C. at a rate of 20 ° C./hour, followed by a reaction at 200 ° C. and 8.3 kPa for 4 hours under reduced pressure. . Table 1 shows various physical property values of the obtained resin a.

Production Example 1 of Amorphous Polyester
The raw materials shown in Table 1 were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, dehydration tube, stirrer, and thermocouple, reacted at 230 ° C for 8 hours, and then at 230 ° C and 8.3 kPa as specified. The reaction was performed under reduced pressure until the softening point of was reached. Various physical properties of the obtained resin A are shown in Table 1.

Production Example 2 of Amorphous Polyester
The raw materials excluding fumaric acid shown in Table 1 were put into a 5-liter four-necked flask equipped with a nitrogen inlet tube, dehydration tube, stirrer and thermocouple, reacted at 230 ° C for 6 hours, and then cooled to 180 ° C. Then, fumaric acid was added. The temperature was raised from 180 ° C. to 210 ° C. at a rate of 10 ° C./hour and reacted for 4 hours, and then a reduced pressure reaction was performed at 210 ° C. and 8.3 kPa until a predetermined softening point was reached. Table 1 shows various physical property values of the obtained resin B.

Examples 1-6, Comparative Examples 1-3
Binder resin shown in Table 2, carbon black “R330R” (Cabot) 6 parts by weight, charge control agent “Bontron N-04” (Orient Chemical Industries) 2 parts and charge control agent “COPY CHARGE PSY” 0.2 parts by weight (manufactured by Clariant), 0.5 parts by weight of polypropylene wax “Viscol 660P” (manufactured by Sanyo Kasei) and 1.0 part by weight of carnauba wax “carnauba wax C1” (manufactured by Kato Yoko) were premixed using a Henschel mixer. After that, using a twin screw extruder “PCM-87” (Ikegai Iron Works Co., Ltd.), feed rate of raw material is 2.5kg / min, rotation speed of screw kneading part is 180r / min, located closest to raw material supply port side the set temperature of the barrel including kneading section [T _1], the set temperature of the barrel adjacent the kneaded portion is including the barrel and the raw material supply port side [T _2] is adjusted to the set temperature shown in Table 2 And kneaded. The obtained melt-kneaded product is cooled with a drum flaker, coarsely pulverized to a volume-median particle size (D ₅₀ ) of 1.5 to 2.5 mm with a cutter mill, finely pulverized with a jet mill, and classified with an airflow classifier. And an untreated toner having a volume median particle size (D ₅₀ ) of 10 μm was obtained.

The configuration of the twin-screw kneader “PCM-87” (manufactured by Ikekai Tekko Co., Ltd.) used for melt-kneading is as follows.
Total length: 2400mm
Screw: 2 Barrels: C0 to C7 from the raw material supply port side (each barrel is 300mm (0.125Lt) in length)
Barrel set temperature: as shown in Table 2 Kneading section: 2 locations at 0.375Lt to 0.5Lt (C3) and 0.625Lt to 0.75Lt (C5) from the raw material supply side

  To 100 parts by weight of untreated toner, 0.3 part by weight of hydrophobic silica “HVK 2150” (manufactured by Clariant) was added, stirred for 200 seconds with a Henschel mixer, and then sieved with a wire mesh having an opening of 100 μm to obtain a toner. .

[Dielectric loss tangent of toner (tanδ)]
Put 5g of toner into a tableting press mold with an inner diameter of 59mm so that the surface is uniform, and set this mold on an electric sample molding machine (C / N: 9302/30, manufactured by Maekawa Tester). A toner pellet having a diameter of 59 mm and a thickness of about 1.7 mm was obtained by applying pressure of 10 tons for 10 seconds with the scale of the attached Bourdon tube load meter. The resulting toner pellets were used in a precision LCR meter; HP4284 and dielectric measurement electrode; HP16451B (electrode used: electrode A) (both manufactured by Yokogawa Hewlett-Packard Company) in an environment at a temperature of 25 ° C. and a humidity of 50%. The dielectric loss tangent (tan δ) of the toner pellets at 1 kHz was measured, and the measured values were evaluated as 0.00 when the measured values were 0.00210 to 0.00400, and as “X” when the others were not. The results are shown in Table 2.

[Toner softening point]
The softening point of the toner was measured according to the above method, and the measured value was evaluated as “◯” when the measured value was 115 to 125 ° C., and “X” when the other value was not. The results are shown in Table 2.

  From the above results, it can be seen that in the toners of Examples 1 to 6, both the dispersion index of the internal additive, tan δ, and the softening point, which is an offset index, are within the appropriate range. In contrast, in Comparative Examples 1 and 3, tan δ is high, indicating that the internal additive is poorly dispersed. Therefore, the toner cannot be a toner that can maintain image quality due to poor charging. Comparative Example 2 shows that tan δ is low and the internal additive is excessively dispersed. For this reason, the charge amount increases excessively, and the low image density and the edge effect become remarkable. Further, since the softening point is lower than that of other toners, the share of melt-kneading becomes tight and the dispersion becomes high, while it is presumed that the molecular chain of the resin is cut by the share.

  The toner obtained by the present invention is suitably used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (6)

A method for producing a toner comprising a melt kneading step, a cooling step, a pulverizing step, a classification step, and a surface treatment step of a raw material containing a binder resin and a colorant,
The binder resin contains 1 to 40% by weight of crystalline polyester and an amorphous resin,
The melt-kneading step has at least a plurality of coupled barrels capable of individually setting the temperature, and one or more kneading units and two or more conveying units inserted into the coupled plurality of barrels. Using a screw as a constituent member, using an extrusion kneader having a raw material supply port at one end of the connected barrel and a kneaded product discharge port at the other end,
The screw has at least one kneading section between the raw material supply side and 0.5 Lt (Lt indicates the total length of the kneader), and includes a barrel (X ) T ₁ the set temperature in, when kneading unit barrel including (X) and a raw material supply port of the adjacent barrel side set temperature T _2, and the melting point of the crystalline polyester and Tc, expression ( a) and (b):
0 ℃ ≦ T ₁ −T ₂ ≦ 50 ℃ (a)
_{5 ℃ ≦ Tc-T 1 ≦} 35 ℃ (b)
A toner production method satisfying 2. The method for producing a toner according to claim ₁ , wherein the screw has a kneading portion between the kneaded product discharge port and 0.5 Lt, and a set temperature of a barrel including the kneading portion is T1. The method for producing a toner according to claim 1 or 2, wherein all the set temperatures of the barrel on the kneaded product discharge side from the barrel (X) are within a range of T ₁ ± 5 ° C.   The method for producing a toner according to any one of claims 1 to 3, wherein the crystalline polyester is obtained by condensation polymerization of a raw material monomer in the presence of a wax.   The toner production method according to claim 1, wherein the crystalline polyester has a number average molecular weight of 3,000 to 10,000 and a weight average molecular weight of 150,000 to 8,000,000.   The amorphous resin contains an amorphous polyester, and the weight ratio of the crystalline polyester to the amorphous polyester (crystalline polyester / amorphous polyester) is 1/99 to 40/60. 5. The method for producing a toner according to any one of 5